Local culinary preferences prompted the acceptance of new staple crops in prehistoric China

The food preparation preferences of Chinese cooks – such as the technological choice of boiling or steaming cereals, instead of grinding them or turning them into flour – have had continental consequences for the adoption of new crops in prehistoric China, according to a research from Washington University in St. Louis.

A new study in PLOS ONE led by Xinyi Liu, an associate professor of archeology in Arts and Sciences, it focuses on the ancient history of staple grains in China, a country well known for its diverse food products and early adoption of many domestic plants.

The authors drew on data from the bones of nearly 2,500 humans to map the changing kitchen patterns over the course of 6,000 years. They argue that the regional differences in food traditions they discovered were not driven by a traditional narrative of “ phases ” of livelihood modalities – i.e., first hunting, then foraging, then herding and finally agriculture – but rather by choices that combined and they discarded livelihoods in many innovative ways over thousands of years.

“In ancient China, subsistence diversity and regional differences coexisted for thousands of years,” Liu said. “It reflected people’s choice, primarily, not their evolutionary state.”

A second deduction from the study concerns the kitchen. The authors suggest that the culinary tradition is one of the main reasons why new grains such as wheat and barley were only gradually accepted by people in central China, particularly in the region near the Loess Plateau, after being introduced from ‘Southwest Asia about 4,000 years ago. But the same new crops were quickly adopted in western China.

“The timing of the relocation of new food crops in prehistoric times reflects a number of choices that different communities had to make,” Liu said. “These choices have sometimes been driven by ecological pressure and sometimes by social conditions or culinary conservatism.

“After 2000 BC, wheat and barley were probably grown in fields in central China. But they did not have the status of staple food in the kitchen or on dining tables. Why they were initially neglected cannot be explained by factors alone. environmental or social. I think the way the cereals were cooked played a role. “

Millet in the north and nuts, tubers, fruit and rice in the south

Grains, including wheat, rice, barley and millet, are the most important food sources in the world today. But understanding how these foods originated and spread around the world requires a global effort.

Liu collaborated with Rachel EB Reid at Virginia Polytechnic Institute (formerly WashU) for this new analysis. They compiled published data of stable carbon and nitrogen isotope compositions measured from 2,448 human skeletal samples from 128 archaeological sites across China. Isotope data from more than 90 previous studies can be read as indicators of the type of food these humans ate predominantly, allowing scientists to identify striking continental-scale patterns.

“By compiling a substantial body of published data on carbon and nitrogen isotopes from all over China, we have had a wonderful opportunity to examine trends over time and space,” said Reid. “We were able to demonstrate not only that staple food choices are deeply rooted and geographically differentiated, but also that culinary traditions may have impacted the reception of new crops.”

They found that, prior to 2000 BC, basic Chinese cuisines were strongly differentiated between northern and southern cultures, while younger cultures were dominated by east-west differences.

“From the beginning, we have seen a contrast in northern and southern cuisine, starting around 8,000 years ago,” Liu said.

The people of the north ate millet, while those of the south ate a variety of nuts, tubers, fruits and rice. Bone records reveal how differences in cooking have become even more pronounced over time.

“One of the key findings is that the tradition of consuming millet as a staple food is very old, and it emerged about 8,000 years ago,” Liu said. “At Xinglonggou, one of the earliest Neolithic sites in southern Inner Mongolia, we estimated that the proportional contribution of millet to the human diet was over 50%. Soon after its domestication, or perhaps while the domestication process was still underway, the millet had become the staple grain food. “

The north-south food distinction in ancient China resonates with the geographical pattern of another ancient agricultural center, the “Fertile Crescent” of Southwest Asia, where human subsistence differed significantly between the northern “hillside” and the southern Mesopotamian flood.

“In both East and West Asia, it appears that early peoples combined subsistence modes into a number of innovative hybrids and moved fairly promptly to other hybrids as they wanted,” Liu said. “Subsistence strategies may be the result of pre-existing social and political conditions, not the other way around, as previously assumed.”

Difference driven by culinary practice

The first north-south gap in staple cereals was driven by environmental differences that favored certain plant resources under different conditions, such as those that fare best in wetlands or arid regions. But the east-west split was driven by differences in culinary practice, with Eastern cooking habits of boiling and steaming less suited to adopting new grains like wheat and barley, Liu and Reid believe.

They cite influential work conducted by two London scholars, Dorian Fuller and Mike Rowlands, which show that early communities were characterized by a difference in food preparation techniques: cooking traditions based on boiling and steaming wheat in Asia oriental and on the grinding of wheat and baking. flour in Western Asia.

“These culinary differences between East and West are deeply ingrained and are probably older than agricultural origins,” Liu said. “Current archaeological evidence suggests that these different cooking technologies are rooted in the Pleistocene, long before the domestication of plants.”

Liu said: “The question is, when grains like wheat and barley that are rooted in the tradition of grinding and baking enter a different cuisine, one that favors boiling, steaming and the consumption of whole grains, what will happen? “

Liu and colleagues have already shown that the introduction of wheat to China may have involved selecting phenotypic traits best suited to the Eastern tradition of boiling and steaming.

The isotope data analyzed in this new study shows a very gradual pace of adoption of wheat and barley as a staple food in central China, unlike a rapid reception of them in western China. The authors relate this to their incompatibility with local wholemeal meals based on boiling and steaming.

“We can always relate those prehistoric lives to our experience of food and cooking,” Liu said. “If nothing else, it takes a lot longer to cook whole wheat kernels with a boil kit, and it tastes very different from boiled rice or millet.”